Made to go onto the HK 3 lug , which has become the standard for 9mm carbines . Shown is the "DD" model , a 1 3/8" dia. can , 10 inches long , which is a narrower tube body then our norm . This is specially designed to fit inside the superb Daniels Defense forearm and attach to the Tros barrel . As you can see , it also works well with other applications . We are doing 2 versions of this , the DD , shown , and our normal subgun tube body which is 1 3/4 dia. . Price for either size can is $675.00